Stock material or miscellaneous articles – Composite – Of silicon containing
Patent
1984-09-13
1987-01-27
Ives, P. C.
Stock material or miscellaneous articles
Composite
Of silicon containing
428448, 428483, 4284769, 4284761, 428576, 4284763, 428 35, 525 12, 2641761, B32B 2732, B32B 1312, B32B 2708, C08L 5106
Patent
active
046393986
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention concerns a compound film containing olefin, wherein at least one polyolefin layer has good adhesiveness to polymers containing polar radicals, such as nylon, polyester and polyolefins.
One of the well-known drawbacks of polyolefins, such as polyethylene and polypropylene, is that their adhesiveness to metals, and to other polymers, is poor. Many methods have been applied in attempts to improve the adhesiveness. As examples may be mentioned the treatment of the polyolefins' surface with acids, with a flame or a corona discharge, or the use of adhesive agents, such as ethylene-acrylic acid copolymers interposed between the polyolefin and the substrate in the case. The adhesiveness of polyolefins to polar polymers has also been improved by admixing to them polymers which possess good adhesiveness, or by copolymerizing polyethylene with monomers containing functional radicals.
Functional radicals improving the adhesiveness may also be obtained by grafting, to the polyolefin chains, various unsaturated polar compounds, such as acrylic acid, methacrylic acid and their derivatives (such as salts), and maleic anhydride.
Very high requirements are nowadays imposed on packaging products especially by the packaging of foodstuffs in plastic films. Therefore, the films intended to be used in packaging food may contain even a great number of separate layers, each one selected to endow the products with a certain characteristic, for instance impermeability to various gases and to water vapor, permeability to certain gases, joinability by seaming etc. In frequent instances a given layer is only required to enable layers with poor adhesiveness, such as polyolefin layers for instance, to be made adherent to other layers containing polar polymers.
The methods employed with a view to improving the adhesiveness of polyolefin layers are encumbered by many drawbacks. For instance, grafting of maleic anhydride or of acrylic acid to polyolefin is risky from the viewpoint of foodstuff applications because said substances can be considered toxic. Furthermore, for instance the adding of maleic anhydride in connection with film extruding operations is difficult and implies the use of solvents.
SUMMARY OF THE INVENTION
The object of the present invention is a compound film wherein at least one polyolefin layer possesses good adhesiveness to polymers containing polar radicals. A further object of the invention is a compound film product in which the adhesive layer contains no substances detrimental to health and which is easy to manufacture. Furthermore one object of the invention is a compound film in which the properties of the adhesive layer are easy to control during the conversion process.
The polyolefin-containing compound film of the invention in which at least one polyolefin layer has good adhesiveness to polymers containing polar radicals is characterized in that said layer consists of polyolefin which has been modified by grafting 0.01 to 10% of unsaturated alkoxysilane.
The silane to be grafted to polyolefins may be any unsaturated alkoxysilane suited to the purpose. Such are, e.g., vinyl trimethoxysilane, vinyl triethoxysilane, vinyl tris(betamethoxyethoxy)silane or gamma methacryloxypropyltrimethoxysilane.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Grafting of polyolefins with silanes is not new in itself. Originally, hydrolysable alkoxysilanes were developed for improving the miscibility of polymers and inorganic fillers (to serve as coupling agents). In such cases, the alkoxy radicals of the silane are hydrolysed to become hydroxy radicals, and thereafter occurs condensation with the hydroxy radicals on the surface of the fillers. These silanes contain, in addition to the alkoxy radicals, one or several radicals having such chemical composition that they mix well with the polymer.
Since the alkoxy radicals or silanes condense by effect of water (and of a catalyst, for instance dibutylstannic dilaurate), silanes have also been introduced in cross-linking technology. Th
REFERENCES:
patent: 4395459 (1983-07-01), Herschdorfer et al.
Chemical Abstracts, vol. 94, p. 38 (1981).
Chemical Abstracts, vol. 96, p. 55 (1982).
Chemical Abstracts, vol. 85, p. 62 (1976).
Patent Abstract of Japanese Application No. 54-61274.
Ives P. C.
Neste Oy
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